1. Field of the Invention
The present invention relates to an uninterruptible power supply apparatus, in particular, to an uninterruptible power supply apparatus which supplies guaranteed power to a plurality of electronic apparatuses which constitute a system.
Recently, costs of personal computers have been reduced and such personal computers have come into remarkably wide use. This situation is a result of users who have used large-size computers now using personal computers in accordance with the current trend of downsizing. In particular, a large number of external storage devices such as hard disk devices are connected to a personal computer server or the like. Also, a network is connected to such a personal computer server. In such a personal computer system, when the personal computer server fails to perform its normal operations, the entire system, for which the personal computer server functions, fails to perform its normal operations. Thus, a very large influence is given to the system. In order to prevent such a situation, guaranteed or backup power supply in case of commercial-power-supply failure or momentary power interruption of the entire system including the personal computer server and peripheral equipment thereof is necessary.
A personal computer server has, for example, an external hard disk device, an external hard disk array, a printer, an external magneto-optical disk device, an external digital audio tape recorder and so forth connected thereto. In such a case, a sequence of power supply start and power supply stop is strictly predetermined among the peripheral equipment. In a case of a commercial-power-supply failure, it is required that an uninterruptible power supply apparatus instead starts supplying power, and a system shutdown process starts. In the system shutdown process, it is required that power supply to the personal computer and the peripheral equipment is stopped in the predetermined sequence. Such an uninterruptible power supply apparatus (hereinafter, referred to as UPS) includes a battery, and, in a case of commercial power supply failure, the battery supplies power to the system including the personal computer and peripheral equipment thereof. Thus, the UPS guarantees a power supply. Further, it is necessary that the UPS has a plurality of output terminals for the personal computer and peripheral equipment, and, through the output terminals, supply power is started (ON) and stopped (OFF) for the respective components of the personal computer and peripheral equipment, individually.
2. Description of the Related Art
For example, Japanese Laid-Open Patent Application Nos. 7-28567, 7-295688, 5-224784, 4-23114 and 63-180117 disclose UPSs in the prior art.
Although a UPS in the prior art may have a plurality of output terminals for supplying power, the output terminals are obtained merely as a result of parallel connection. Accordingly, it is not possible to set power supply start/stop timing individually among the respective output terminals. Further, when a plurality of UPSs in the prior art are used in a personal computer system, power supply by the UPSs can be started/stopped neither all at once nor in a predetermined sequence. Further, it is not possible to control a plurality of UPSs by a single personal computer.
In a UPS in the prior art, it is not possible to set a power supply start/stop sequence/timing individually among the respective ones of a plurality of output terminals. Accordingly, it is not possible to set sequence/timing of a power supply start/stop among the respective components of a system including a personal computer and peripheral equipment such as an external hard disk device, an external hard disk array, printer and so forth. As a result, when a commercial power supply failure occurs and the system including the personal computer and peripheral equipment is stopped, or a commercial power supply starts and the system is started, power supply to the entirety of the system (including the personal computer and peripheral equipment) is stopped all at once or is started all at once.
Further, in a personal computer system to which a power supply is guaranteed, there is a case where peripheral equipment such as an external hard disk device, and an external hard disk array, an external magneto-optical disk device and an external digital audio tape recorder is additionally provided. In such a case, a new UPS is provided for the additionally provided equipment. As a result, there is a plurality of UPSs in the single personal computer system. However, in the prior art, when a plurality of UPSs are used to the system, power supply by the UPSs is started/stopped neither all at once nor in a predetermined sequence. Accordingly, it is not possible to set the power supply stop/start sequence/timing for the personal computer and peripheral equipment in the personal computer system. Further, the UPS, which is originally connected to the personal computer for power supply in the personal computer system before the additional provision of the peripheral equipment, transmits various kinds of information to the personal computer and receives various kinds of information from the personal computer. The information transmitted to the personal computer from the UPS includes the remaining battery power of the remaining battery life (the number of repetitive charging and discharging operations), the voltage of the commercial power supply, the current consumed by the loads, and so forth. The information transmitted from the personal computer to the UPS includes a power supply stop time for the night and a power supply start time for the following morning. However, in the prior art, it is not possible that a single personal computer controls a plurality of UPSs. The amount of information which can be transmitted and received between the personal computer and UPS is limited to the number of interface terminals of the personal computer provided for the UPS. As a result, the above-described information transmission and reception cannot be performed between the personal computer and the new UPS provided for the additionally provided peripheral equipment.